磷炔R-C≡P(R=-BH_2,-CH_3,-NH_2,-OH)及其异构体的稳定性

The Stability of Phosphaalkynes R-C≡P (R=-BH_2, -CH_3,-NH_2,-OH) and Their Isomers

采用B3LYP和CCSD(T)方法对R-C≡P(R=-BH2,-CH3,-NH2,-OH)体系进行了理论研究.结果表明,含C≡P三键的异构体BH2-C≡P和CH3-C≡P在各自的体系中分别是热力学最稳定的结构.而在HO-C≡P和NH2-C≡P体系中,热力学最稳定的结构却是H-P=C=O和含C≡N三键的N≡C-PH2.动力学理论研究表明,没有相关实验研究的R-C≡P(R=-BH2,NH2)体系中共有5种异构体是动力学稳定的.在HO-C≡P体系的2种动力学稳定的异构体中,H-P=C=O连接方式的异构体已被实验所证实,而另外一种HO-C≡P连接方式的异构体的动力学稳定性较高,实验中可以观察到.对于CH3C≡P体系,研究所预示的2种动力学稳定的异构体中CH3-C≡P已被实验证实,从理论上推测另一种动力学稳定性较高的异构体HC≡C-PH2在实验中也可以检测到.

B3LYP and CCSD(T) methods were employed to investigate the systems of R-C≡P(R=-BH2, -CH3,-NH2, -OH). The results indicate that isomers P≡C-BH2 and CH3-C≡P containing C≡P triple bond are thermodynamically the most stable species in BH2-C≡P and CH3-C≡P systems, respectively. But in the systems of HO-C≡P and NH2-C≡P, H-P=C=O and N≡C-PH2 containing C≡N triple bond are thermodynamically the most stable species, respectively. The calculated results on the kinetic stability indicate that for R-C≡P(R=-BH2,-NH2) systems, in which no experimental information are available, fiveisomers are kinetically stable. In HO-C≡P system, two kinetically stable species are located. Isomer H-P=C=O has been detected in experiment, and in viewof higher kinetic stability, another isomer HO-C≡P should be experimentallyobservable. For CH3-C≡P system, isomer CH3-C≡P has been observed in experiment, and another kinetically stable isomer HC≡C-PH2 ought to be detectedin future experiments.